NEWTON, Iowa—Ron DeSantis declined in an interview broadcast Sunday to say whether he would step aside if he fails to secure a win or second-place showing in the Jan. 15 Iowa caucuses, as he tries to fight off a strong challenge from Nikki Haley to be the only serious alternative to Donald Trump in the Republican presidential primary race.

“We’re going to win Iowa,” the Florida governor said on NBC’s “Meet the Press” program. “It’s going to help propel us to the nomination. But I think we’ll have a lot of work that we’ll have to do beyond that. I don’t think you take anything for granted.”

DeSantis and Haley, a former South Carolina governor and United Nations ambassador, are set to appear in a debate in Alabama on Wednesday that might feature as few as three candidates. Trump, the former president and nomination front-runner, won’t participate and has skipped all three previous primary debates.

Former New Jersey Gov. Chris Christie said Sunday on CBS’s “Face the Nation” that he was confident he would meet the Republican National Committee’s fundraising and polling requirements for debate participation. Entrepreneur Vivek Ramaswamy is expected to qualify.

DeSantis drew a burst of much-needed media attention last week for his feisty televised debate with California Democratic Gov. Gavin Newsom.

Despite his upbeat projections, DeSantis faces increasing turbulence. Internal turmoil continues to plague Never Back Down, a super PAC supporting him that has played an outsize and nontraditional role by handling many of the tasks normally handled by a campaign.

In recent days, top people working with the PAC have left, either by resignation or firing, adding to a portrait of disarray. Among those who quit are Chris Jankowski, who served as chief executive. His successor, Kristin Davison, was fired only days into the job.

On Saturday, DeSantis completed his tour of all 99 Iowa counties. He has heavily focused his campaign on the state that will start the nomination process and contends that emphasis and a well-funded ground organization will be rewarded with strong support there.

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